Rex had infant eczema — not exactly a photogenic condition. It started with scaly red patches on his face and extremities, but within two weeks he was covered with a weeping bumpy rash.

Ms. Harris was at a loss. “We had tried everything the pediatrician recommended, but Rex was feverish and in distress. So we took him to the emergency room and they told us they’d never seen eczema so bad,” she said.

Babies, with their delicate skin, can be a lot like teenagers when it comes to skin afflictions. Common conditions such as neonatal and infantile acne, milia and cradle cap can ignite worries, and even cause some parents embarrassment (though they might be ashamed to admit it). In that first year of a baby’s life, who doesn’t want to capture that darling baby on film and in pixels, looking, well, darling?

But infant eczema, with its unpredictable outbreaks and vicious cycle of itch and scratch, has been raising discomfort for babies and anxiety in parents to a new level.

“It used to be, 20 years ago, one baby in 20 was affected by it,” said Dr. Anthony Mancini, a pediatric dermatologist in Chicago and head of dermatology at the Northwestern University Feinberg School of Medicine. “Now, that number is roughly one in five or six.”

“It’s got to have something to do with our Western lifestyle,” said Dr. Hugh Sampson, a professor of pediatrics and immunobiology at the Mount Sinai School of Medicine in Manhattan, and president of the Academy of Allergy, Asthma and Immunology. “There are issues of pollution, preservatives, the potency of pollen.”

Others mention the use of harsh laundry detergents and soaps. And then there is the hygiene hypothesis, which, Dr. Sampson said, “certainly has as much supportive data as anything.”

Developed in 1989 by the British epidemiologist David P. Strachan, the hygiene hypothesis was his explanation for the finding that eczema and hay fever were less common in children from larger families, who were presumably exposed to more infectious agents through their siblings, than in children from families with only one child. The theory goes on to suggest that as one’s immune system is no longer challenged to fight off the infections that we now combat with antibiotics, the system overreacts to allergens.

Which doesn’t mean that infant eczema will last forever. “Studies have shown that at least half of the children with the condition will outgrow it,” said Dr. Sarah Chamlin, a pediatric dermatologist in Chicago. “But, in the meantime, that young child’s life and that of his or her family is greatly impacted.”

Along with the baby rubbing and scratching through the night, Dr. Chamlin said, parents were often distressed to find their child had opened up the skin and bloodied the bedding.

“The parents I see are often exhausted and exasperated,” she said. “I have had parents report accusations of child abuse, because how could anyone let their young child look like this?”

Infant eczema cannot be cured, Dr. Chamlin said, but it can be managed — though treatment is often a minefield. Each course of action seems to carry with it the weight of differing opinions and erratic results: whether or not to use low-dose topical steroids, administer antihistamines, or try new nonsteroidal ointments that carry F.D.A. safety warnings. Even whether to bathe or not becomes an issue.

“When at last you think you’ve found something that works, it doesn’t mean it’s going to work for long,” said Angel McCutcheon of Antioch, Tenn., whose daughter Brandy, now 12, has had severe eczema since she was a baby.

“Admittedly, it can be a very frustrating process,” said Vicki Kalabokes, the chief executive officer of the National Eczema Association (www.nationaleczema.org), which recently began a program that offers qualifying products — including Cetaphil Moisturizing Lotion and Triple Cream Severe Dry Skin/Eczema Care — a seal of acceptance. “There are a zillion products out there,” Ms. Kalabokes said.

Indeed, the baby product market has boomed in the last decade with irresistibly packaged and fragranced cleansers, moisturizers, wipes and sunscreens that claim to be gentle and natural.

“Just because it’s natural doesn’t mean it’s good for you — think of poison ivy,” said Dr. Elaine Siegfried, a pediatric dermatologist in St. Louis.

While, according to Dr. Siegfried, a product is not going to cause infant eczema, it can exacerbate it and may cause secondary contact dermatitis, in which areas of the skin not affected by eczema can become irritated.

“To me the best skin care regime for a baby with sensitive skin is plenty of hydration, a bath a day, followed immediately by an application of plain old petroleum jelly,” said Dr. Siegfried.

High on the list of baby skin irritants are fragrance, color and preservatives like Kathon and propylene glycol.

“I tell patients, ‘Read the label,’ but I have a medical degree and can’t always figure out what goes into a product,” Dr. Siegfried said. “One popular so-called natural baby product doesn’t even identify its preservative, which can be highly allergenic to a baby, but instead lists the preservative on the label as a ‘proprietary ingredient.’ ”

In a small study of 20 children at high risk for infant eczema, Dr. Eric Simpson, a dermatologist and assistant professor at Oregon Health and Science University is studying the effects of a daily moisturizing regime using Cetaphil Moisturizing Cream for Dry Sensitive Skin.

“I’m trying to find out if a healthy skin regime can in fact protect the skin barrier and prevent infant eczema from occurring in babies who either have a parent or sibling who has presented with eczema,” he said.

So far, only 2 of the 20 babies have developed the condition, and not on their faces, which is where 90 percent of infant eczema usually occurs first, Dr. Simpson said. “To me it’s suggestive that it’s a feasible treatment worthy of further study,” he said.

Lauren Allen of Vancouver, Wash., whose daughter is in the study, has been a lifelong eczema sufferer herself.

“It would get so bad, the pigment on my face would change,” Ms. Allen said.

Her older daughter, Eva, now 3, has suffered from eczema since she was an infant, but for her younger daughter, Grace, born last year, Ms. Allen said, “I hauled that big tub of cream to the hospital with me, and right after her first bath, put it on her.”

And, so far, said Ms. Allen, Grace’s skin has been clear.

“I don’t want either of my daughters to ever be afraid to show off their beautiful skin,” she said.